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Aug. 20, 2012 -- A new study is raising fresh concerns about the use of general anesthesia in young children.

Recent studies have suggested that anesthetic drugs may increase the risk for learning disabilities and behavioral problems such as attention deficit hyperactivity disorder (ADHD), but only in kids who are exposed to the drugs several times.

The new study, which is published in the journal Pediatrics, links even a single dose of anesthesia to later harm.

"If children need to have surgery, you need to weigh all the risks and all the benefits in terms of what you need to do," Sun says.

Anesthesia Study

The new study is based on data from nearly 2,900 children in Australia followed by researchers since before they were born.

Parents reported that 321 children in the study had medical procedures that required general anesthesia before age 3. The other 2,287 children weren't exposed to the drugs.

When the children were 10, researchers tested how well they could learn, think, remember, reason, and use language. Doctors also asked questions about their behavior and any problems like depression or aggression.

Kids who were given anesthesia before age 3 were more likely to have learning problems by age 10 than other children.

Children who got anesthesia as toddlers, for example, weren't able to use language as well as their peers. They also had more trouble solving problems.

There could be other explanations. Children who need surgery early in life might have other medical conditions that hurt their brain development in some way.

But the researchers say they don't think that's the case since most procedures performed in the study were minor. Those included common childhood surgeries including inserting ear tubes to help kids with chronic ear infections, hernia repairs, circumcisions, removing a child's tonsils, and dental procedures.

Even after accounting for things that are known to have an impact on brain development, such as mom's education, low birth weight, and household income, exposure to anesthesia was still linked to the likelihood that a child would have difficulty using language.

Children exposed to anesthesia were more than twice as likely to have a language disability. In particular, it increased the chance that a child would have trouble listening to and remembering spoken words.

Anesthesia was also tied to a 73% increased chance that a child would have trouble with abstract reasoning. Multiple exposures to anesthesia further raised a child's risk for problems.

The researchers found no link between anesthesia and behavioral problems or attention, however.

Unanswered Questions

The study leaves many important questions unanswered.

Because the researchers didn't have access to the children's medical records, they weren't able to tell which drugs were used or how long the procedures lasted.

And the most commonly used drug for anesthesia in children during the study years was halothane, a drug that's since been discontinued.

Newer drugs that have replaced it work in much the same way, so the study findings are probably still relevant, says Randall Flick, MD, a pediatric anesthesiologist at the Mayo Clinic in Rochester, Minn.

Even nitrous oxide, which is often used in dental procedures, is a concern, he says.

"Nitrous oxide has its own set of problems in addition to neurotoxicity. Most people in pediatric anesthesia are getting away from using nitrous oxide for any reason," though dentists, he says, haven't made the switch.

"I don't think at this point in time that one can say this is absolutely the anesthesia. It could be that anesthesia is a marker for this type of thing," Sun says.

Other experts who weren't involved in the study agree that it's too early to sound the alarm.

"The study is very well done and is an important study, but we have to be careful about over-interpreting," Flick says.

Flick chairs an FDA committee that's looking into the safety of sedating drugs in children.

After a meeting last April to review the evidence, "It was the consensus of the group that there should be no communication to the American public regarding this concern because the evidence wasn't sufficient to warrant that," Flick says.

Research in animals shows that anesthetic drugs can speed up cell death and may keep developing brains from forging important connections between neurons.

Evidence in humans, however, is mixed and less direct.

Advice to Parents

Deciding whether a child should have surgery is always difficult. The risks from anesthesia are something to consider.

But what are the risks, exactly? Experts say that's a question that doesn't have a good answer.

"We don't know whether the problem is a real one, and if it's a real one, we don't know how to avoid it," says Michael Roizen, MD, an anesthesiologist who is chief wellness officer at the Cleveland Clinic, in Ohio.

Roizen also chairs the SmartTots campaign, which is a joint project of the FDA and the International Anesthesia Research Society. SmartTots is funding studies on the safety of anesthesia in kids.

Until more is known, Roizen says parents shouldn't panic.

"If the child needs surgery, there is no way of avoiding [anesthesia] right now," Roizen tells WebMD. "The goal is to have the shortest period of time of anesthesia as possible."

If the procedure is a minor one, parents should work with their child's doctor to see if it can be delayed.

"If it is tubes or tonsils and it can be put off until after age 3, then it should be put off," Roizen says.

Flick says some procedures, such as hernia repairs, can be done with regional anesthesia, which numbs part of the body, as opposed to general anesthesia. There's no evidence suggesting one approach is better than the other.

It's also a good idea to meet with your child's anesthesiologist to ask what drugs may be used. In general, Flick says, "Single, brief anesthetics typically do not cause a problem."